Proposal Generation. Anchor-free methods such as SSN [1]}, BSN [2]}, BMN [3]}, DBG [4]}, BC-GNN [5]}, BU [6]}, and BSN++ [7]}, A2Net [8]} and AFSD [9]} achieved superior results compared with anchor-based methods such as Yeung et al. [10]}, SMS [11]}, TCN [12]}, SCNN [13]}, TURN TAP [14]}, CBR [15]}, and CDC [16]}. This is because anchor-free methods generate temporal action proposals with more flexibility and precise temporal boundaries. Some methods such as CTAP[17]}, MGG[18]}, PBRNet [19]}, SRG[20]}, and RapNet [21]} combine advantageous of anchor-based and anchor-free methods and attained a higher results.
